Duchenne muscular dystrophy carriers

Two of my baby brothers have Duchenne muscular dystrophy, my mother is a carrier. My question is if I am a carrier would I get symptoms as I age? And what are the chances of me being a carrier?

- A curious woman from Virginia

February 8, 2019

These are great questions! There is a 50% chance that you are a carrier for Duchenne muscular dystrophy (DMD), just like your mother. 

Typically, carriers for DMD do not have any problems. But 20% of DMD carriers do have some symptoms, though not as severe as someone with the full disease.

Let’s take a step back and think about what causes Duchenne muscular dystrophy, as this will help explain what it means to be a carrier.

Chimerism and transgender

I was born male, and received a bone marrow transplant from my sister to treat leukemia.  A bone marrow aspiration a few years back concluded I had female DNA in my marrow, while a normal blood test would show male. 1) By this fusion am I a chimera? 2) Would I have an extra sex chromosome? And finally, I recently came out as trans (M to F). In my case, am I genetically trans? Or getting my hopes up?

- A curious adult from New Hampshire

February 2, 2019

Chimeras have Two different sources of DNA

You’re absolutely right that you are a chimera. The term chimera refers to any time someone has two different sources of DNA in their body. 

In your case, you have two different sources of DNA in your body: your own DNA, and your sister’s DNA. But it won’t be randomly mixed together! 

Epigenetics and cell types

How do epigenetic changes affect an entire organism, instead of just individual cells? Shouldn't it just affect the cell(s) that have had their DNA affected?

- A high school student from Australia

January 17, 2019

One really important thing that epigenetic marks do is define the different cell types and organs that make up our body. Epigenetic marks can change how a cell reads the DNA instructions.

This causes some cells to read certain genes more, while others will read those same genes less. These differences help give us the wide variety of cell types in our bodies – even though they all have the exact same DNA!

Long eyelash genetics

Are long eyelashes a genetic trait?

- A high school student from Australia

November 29, 2018

In some cases, yes! Eyelash length definitely is influenced by genetics, but there are other factors that can affect it too. 

Medically speaking, “long eyelashes” are defined as longer than 12mm in length. This is known as eyelash trichomegaly

How paternity tests work

How exactly do paternity tests work?

I have recently had a paternity test carried to determine if a man is my father. They tested 24 markers and we matched on 14 of them. The testing company said that he can't by my father. My question is how can two people have 14 matching markers and not be related?

- A curious adult from the UK 

November 29, 2018

Paternity tests can be hard to understand.  Matching with someone at 14 out of 24 markers seems like a lot, but these tests are designed so that a father and child should completely match.  

Rhesus Factor Evolution

What is Rhesus factor? Did we get it from Rhesus monkeys? Can Rh factor be found in other animals?

-- A curious adult from Arkansas

November 20, 2018

Rhesus factor is a part of your blood type. It’s the “+” or “-“ in A+, B-, O+, etc.

Heterochromia

What causes heterochromia?

- A curious adult from Texas

September 24, 2018

There are several ways people can have two different colored eyes. People can be born with heterochromia, or it can result from disease or injury. It’s pretty rare for people to inherit mismatched eyes from their parents.

But before diving into the details, we need to understand where eye color comes from. 

Is happiness genetic?

If I'm happy a lot, is that a trait?

- An elementary school student from Washington

August 17, 2018

Great question! First, let’s see what a "trait” is. 

A trait is just something that describes a person or thing. For example, tables usually have 4 legs. So we could say one of the traits of a table is having 4 legs! 

So if you are happy a lot, that’s absolutely a trait – it describes you! And since it describes how you feel or act, we would call it a personality trait

Balding Genetics

What if my father had the trait for baldness and my mother didn't? What chance will I or my future offspring be carriers or have the trait?

- A high school student from Michigan

August 1, 2018

If your mom’s dad is bald, then there’s a high chance you’ll go bald in the future! If your father is bald as well, then those chances go up even more! But even if baldness doesn’t run in your mom’s family, it’s still possible you’ll go bald.

(I’m assuming that you’re male, since if you’re female then you don’t have to worry so much. Female hair thinning is a very different process that involves different genes.)

The X chromosome isn’t the only one to blame
The crucial baldness gene found on the X chromosome only contributes in some part to baldness. Several other genes scattered across your other chromosomes can also turn you bald.

This means your dad can pass on some of those other baldness genes to you! You have a chance of going bald even if your mom doesn’t have baldness in her family.

Can we make a miniature elephant?

Is there a particular gene that controls size of mammals? For example, could you manipulate a particular gene in an elephant to miniaturize it?

How does proportional size work on mammals? Could you increase or decrease the size of an elephant's trunk by manipulating genes? 

- A curious adult from Oklahoma

July 30, 2018

Animal size is a complex genetic trait. There are many genes that are involved in determining an animal’s overall size. 

Not only that, one gene can also affect many traits! Many of the genes that affect body size also affect other things such as metabolism or lifespan. 

Is it possible to change the size of an elephant’s trunk?

The short answer is maybe, but not right now. We still don’t know exactly which genes are responsible for the elephant’s long trunk. If we knew what they were, we might be able to make an elephant with a shorter or longer trunk. 

But remember that a gene may affect multiple body parts! I mentioned that growth hormone mutations can make an animal (or person!) bigger or smaller. But those mutations can also lead to diabetes, high blood pressure and memory loss.

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